Clinical, neuroimaging, and laboratory features are not specific enough to establish the etiological diagnosis of the acute inflammatory myelitis (AIM). Longitudinally extensive transverse myelitis (LETM) seen on magnetic resonance imaging (MRI) has been associated with a poor functional prognosis. The aim of this study was to assess the functional outcomes of a first AIM event comparing patients with LETM vs. no LETM on MRI and to report the differential diagnosis. Clinical, radiological, biochemical aspects were collected, and Winner-Hughes Functional Disability Scale (WHFDS) was performed after 3 and 6 months. Centromedullary lesions were associated with LETM, lateral lesions with partial lesion (PL), and brain MRI lesions with multiple sclerosis and acute encephalomyelitis disseminated. LETM patients were associated with a worse functional outcome as the need of a wheelchair after 3 and 6 months (OR = 7.61 p = 0.01; OR 4.8 p = 0.04, respectively), a walker or cane (OR = 11.0 p = 0.002, OR = 4.3 p = 0.03, respectively). In addition, we found a correlation between LETM and acute complete transverse myelitis and PL with acute partial transverse myelitis (83.3 and 90.9%, respectively; p < 0.0001). In conclusion, AIM is a heterogeneous syndrome from an etiological point of view and LETM patients had worse functional prognosis compared with PL after 3 and 6 months.
Keywords: Longitudinally extensive transverse myelitis; Multiple sclerosis; Neuromyelitis optica; Partial myelitis; Prognosis; South America.